Process of making organic-acid anhydrids.



RUDOLF soMM E-R,

OF VIENNA,AUSTRIA-HUNGARY.

IPIROICEISS 0F MAKINGQRGANIC-ACID ANHYDRIDSL,

T 0 all whom it concern.- Be it known that I, RUDOLF SOMMER, chemist, asubject of the Emperor ofAustria-Hungary, residing at Wahringerstrasse 59, Vienna, IX, in the Empire of Austria-Hungary, have invented new and useful Improvements in Organic-Acid Anhydrids and Process of Making Same; and I do hereby declare the following to be afull, clear, andexactdescription of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the production of anhydrids of the organic acids;

The methods hitherto adopted for produclng organic-acid anhydrids are as follows: (a) by the action of acids or acid salts on acid chlorids, (b by the reaction of phosphoric pentoxid upon the acids, (0) by passing phosgene or bisulfidof carbon over the heated salt, (d) by the reaction between sulfuryl chlorid and salts of the acids, (e) by the action of chlorin dioxid and sulfur-dioxid gas upon the salts, (f) by the treatment of the salts with aromatic sulfo-acid chlorids, and (g).by sulfur chlorid.

According to my invention I transform the acids intotheiranhydrids by acting upon the heated dehydrated salts of the acids with tetrafiuorid of silicon. I have found that by the employment of this substance, which is of low cost and easily obtainable, I am enabled to produce anhydrids with facility. I have also found that tetrafluorid is yielded from the residueobtained on the distillation of the anhydrids by treating it with sulfuric acid with the addition of some sand.

vention to be fully understood:

1. Tetrafluorid, obtained, for example,- by heating two parts of fluor-spar and two parts of sand with two parts of concentrated sulfuric acid, is first treated with a heated mixture of sand and sulfuric acid and is then passed into'one part of dehydrated sodium acetate heated to a temperature of about 200 to 220 centigrade. The gas is quickly absorbed, and as soon as the absorption is complete the anhydrid which is formed commences to distil over. The unused gas is con- .veyed into a second and then into a third abspe'cification of Letters Patent. Application filed June 22, 1905. Serial No. 266,400. (Speoimensi) sorption vessel. The acetic-acid anhydrid,

Patented Dec. 12, 1 905.

which isformed approximately q uantitatively,

practically all passes over with the first dis'til' late at about 138 centigrade.

2. .Two parts of the residue of distillation obtained in the previous example are heated with one part of sand and two,parts of oon- V centrated sulfuric acid,-' and thegas which 'is generated after being'dried is conveyed into potassium benzonate heated'to about 200 centigrade. When no further absorption takes place, extraction with benzin is effected. The

crystals, which meltat42 centigrade, consist of pure anhydrid. WhatI claim as my invention, and desire to secure by Letters Patent, is

- 1. The method of producing acid anhydrid from dehydrated salts of the acids, consisting in subjecting a dehydrated salt to the action of tetrafluorid of silicon.

2. The method of producing acid anhydrid from sodium acetate, consisting in subjecting heated sodium acetate to fluorid of silicon.

3. The method of producing acid anhydrid from dehydrated salts of the acids, consisting in treating tetrafluorid of silicon with'a heated mixture of sand and sulfuric acid, and then passing the tetrafluorid of silicon into a dehydrated salt.

the action of tetra- 4. In the production of anhydrid from de- 1 hydrated salts of the acids, the steps consisting in subjecting heated dehydrated salt to the action of tetrafluorid of silicon, heating the residue of such distillation with sand and sulfuric acid, drying the gas generated, conveying the dried gas intoa heated benzoicacid salt, and extracting with benzin. The following examples will enable the in- RUDOLF SOMMER.

- Witnesses:

WENZEI. LINKE FREY, ALVESTO S. HOGUE. 

